Question

Find the angle between the pair of lines r=3i + 2j − 4k + λ (i + 2j + 2k) and
r = 5i −2k + μ (3i + 2j + 6k).

A. Cos⁻¹ (19/21)
B. Sin⁻¹ (19/21)
C. Cos⁻¹ ( 20/21)
D. Sin⁻¹ (20/21)